1. Field of the Invention
The present invention relates to a transparent electrode laminate and a touch screen panel including the same, and more specifically, to a transparent electrode laminate with low pattern visual recognition and a touch screen panel having the transparent electrode laminate.
2. Description of the Related Art
Commonly, a touch screen is a screen equipped with a special input device to receive positional input by touching the screen with a finger of a user or a stylus pen. Such a touch screen does not use a keyboard, but has a configuration of multi-layer laminates wherein when the finger of the user or an object, such as a touch pen or a stylus pen, touches a specific character or position displayed on the screen. The touch screen identifies the position and directly receives data from the screen in order to practically process information at a specific position via software stored therein.
In order to recognize the touched position without degrading the visibility of an image displayed on the screen, it is necessary to use a transparent electrode in which sensing patterns are, in general, formed in a predetermined pattern.
As a transparent sensing electrode used in the touch screen panel, various structures are known in the related art. For example, a glass-ITO film-ITO film (GFF), a glass-ITO film (G1F), or a glass only (G2) structure may be used in the touch screen panel.
Among these, GFF is a commonly used structure and includes two transparent electrodes (viz., indium tin oxide, (ITO)) formed with two films required to implement X-axes and Y-axes. The G1F includes a first ITO thin film disposed on a rear surface of a glass and uses a film as a second ITO. G2 is a structure formed by a method depositing and patterning an ITO thin film for an X-axis on a rear surface of one reinforced glass, forming an insulation layer thereon, and pattering another ITO thin film for a Y-axis. Transmittance in the GFF, G1F, and G2 is increased while the power consumption is reduced, therefore, studies for the G2 structure are actively pursued.
However, in the G2 structure, which uses a patterned transparent electrode, a patterned portion and a non-patterned portion (i.e., pattern opening) of the transparent electrode may be visually distinct from each other. Accordingly, the bigger the difference in reflectance between the patterned portion and the non-patterned portion means the more distinctive the reflectance difference, and therefore, a decrease in the visibility of the appearance of a display element. In particular, in a capacitive-type touch panel, since patterned transparent electrodes are formed on the entire surface of the display unit of the display, even if the transparent electrode layer is patterned, the display device needs to have a good appearance.
In order to improve such a problem, for example, Japanese Patent Laid-open Publication No. 2008-98169 discloses a transparent conductive film in which an under coat layer including two layers with different refractive index is formed between a transparent substrate and a transparent conductive layer. In addition, as an embodiment of thereof, the above-described patent further discloses a transparent conductive file in which a silicon-tin oxide layer having a refractive index of 1.7 (with a thickness of 10 nm or more), a silicon oxide layer having a refractive index of 1.43 as a low refractive index layer (with a thickness of 30 nm), and an ITO film having a refractive index of 1.95 (with a thickness of 15 nm) are sequentially formed in this order.
However, since the difference in reflectance between the patterned portion and the non-patterned portion is clearly noticeable in the transparent conductive film disclosed in the above-described patent, there is still need for improvement of the appearance of the display device.